US 6,936,508 B2 · Metal gate MOS transistors and methods for making the same

Abstract

Semiconductor devices and fabrication methods are provided, in which metal transistor gates are provided for MOS transistors. Metal boride is formed above a gate dielectric to create PMOS gate structures and metal nitride is formed over a gate dielectric to provide NMOS gate structures. The metal portions of the gate structures are formed from an initial starting material that is either a metal boride or a metal nitride, after which the starting material is provided with boron or nitrogen in one of the PMOS and NMOS regions through implantation, diffusion, or other techniques, either before or after formation of the conductive upper material, and before or after gate patterning. The change in the boron or nitrogen content of the starting material provides adjustment of the material work function, thereby tuning the threshold voltage of the resulting PMOS or NMOS transistors.

Claims30

Dependent claims

A method of fabricating PMOS and NMOS metal gate structures in a semiconductor device, the method comprising:

forming a gate dielectric in PMOS and NMOS regions above a semiconductor body;
forming a metal nitride above the gate dielectric in the NMOS region;
forming a metal boride above the gate dielectric in the PMOS region;
patterning the metal nitride to form an NMOS gate structure in the NMOS region;
and
patterning the metal boride to form a PMOS gate structure in the PMOS region;
wherein forming the metal boride above the gate dielectric in the PMOS region comprises:
forming a metal nitride above the gate dielectric in the PMOS region;
and
introducing boron into the metal nitride to form the metal boride in the PMOS region.

7 more elements

Dependencies are inferred from the claim text.

Metal gate MOS transistors and methods for making the same

Life of this patent

Metal gate MOS transistors and methods for making the same

Life of this patent

Abstract

Claims30